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JET performance brings promising signs for ITER | 23/11/2016

The latest JET experiments, which came to an end on 15 November, have met all expectations – achieving the best results in the past five years of high power operation.

The excellent machine reliability and routine high heating power in the experimental campaign was pleasing for the JET engineering team, and was also very good news for European fusion physicists.

In recent years, there has been painstaking development of two plasma scenarios that will be the standard for ITER operation: a so-called ‘baseline' which relies on the increase of plasma current to achieve high performance, and the so-called ‘hybrid' that relies on higher plasma pressure to achieve similar performance but at lower plasma current. Until now, these scenarios had not been tested with such high heating power with JET's ‘ITER-like' inner wall of beryllium and tungsten; initial results from the latest campaign showed excellent plasma confinement, high stored plasma energy (over 9 megajoules) and significant neutron yield.

All of this was very reassuring for researchers, demonstrating their scenarios could sustain high plasma performance with the ITER wall materials without showing excessive accumulation of beryllium and tungsten in the plasma. This provides confidence that JET's eagerly anticipated deuterium-tritium campaign in 2019/20 is on track to be a success and that ITER plasma development – based closely on these two scenarios – is also well developed.

Head of the JET Exploitation Unit, Lorne Horton, said: “These are the weeks the team really works for – where all the hard work in preparation yields positive results. High machine reliability, high heating powers and good plasma diagnosis has really meant that we are in a great position to fully exploit deuterium-tritium operation in the coming years.”

One of the main objectives of the campaign was to reliably achieve high neutral beam heating power (around 25 megawatts). The challenge has been met: in just one month, an impressive 68 high power pulses were generated. This is more than the entire number obtained over the past five years. The Ion Cyclotron Resonance Heating system also performed very well and delivered 60 pulses at high power level (5 megawatts).

Dragoslav Ciric, Tokamak Operations Manager at CCFE, added: “I haven't seen so many smiley faces in the Control Room for many years. This is the best indicator of how well JET performed during the campaign – the operations team did a fantastic job.”